Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the full burden and does well: it discloses that the call costs 0 AU and is never blocked by the session budget, which is critical non-obvious behavior for a metered API. It does not explicitly label the operation read-only or describe auth requirements, leaving a small gap.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two sentences, front-loaded with the resource and its returned fields, then the timing guidance. Dense and mostly waste-free, though the long list of return values is slightly inventory-like.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

No output schema exists, but the description enumerates the returned values, and with no annotations it covers cost and budget behavior. What remains thin is the operational boundary: auth/scope requirements for 'YOUR organization' are only implied.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The tool takes zero parameters, so the baseline is 4; there is no parameter semantics to add and the description correctly adds none. The enumerated return fields substitute usefully for a missing output schema.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb (check) and resource (billing period usage for the organization) and enumerates exactly what is reported: plan, included AU, used AU, remaining AU, overage, and per-minute rate limit. An agent can distinguish it from the only sibling, analyze_contract, without opening either schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Gives explicit invocation timing: before large metered jobs (with concrete examples like theme extraction over many reviews, long contracts) and after quota errors. No when-not-to-use condition or named alternative, but the lone sibling is not a plausible substitute, so the guidance is effectively complete.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.